Method and apparatus for folding sheets such as drawings

ABSTRACT

Large sheets such as drawings having any of various lengths are folded into packets of standard length in the direction transverse to the folds by feeding the sheets individually past length measuring points spaced apart along a pathway to a zigzag folder which is actuated at intervals determined by a computing control system in response to signals received from sheet detectors located at the measuring points. The detectors sense simultaneously a certain location of the leading edge of each sheet and the presence or absense of the sheet at other points in the pathway, thus determining the folding pattern to be applied to the sheet; and as the sheet is advanced the control system measures the residual length, if any exists, by which the sheet trails a point where its presence was sensed and determines correspondingly the locations of certain folds. When a sheet is longer than the length ranges defined between the detectors, its leading part is folded into panels having the desired packet length until the trailing edge has been brought into a range between two detectors, whereupon the residual length and corresponding fold location(s) are determined.

United States Patent 1191 Van Herten [4 Aug. 27, 1974 METHOD ANDAPPARATUS FOR FOLDING SHEETS SUCH AS DRAWINGS [75] Inventor: Jozef MarieVan Herten, Venlo,

Netherlands [73] Assignee: Oce-Van der Grinten N.V., Venlo,

Netherlands [22] Filed: Apr. 9, 1973 [21] Appl. No.: 348,883

Related US. Application Data [63] Continuation-in-part of Ser. No137,549, April 26,

1971, abandoned.

[] Foreign Application Priority Data Apr. 10, 1972 Netherlands 7204777[52] US. Cl. 270/79 [51] Int. Cl Bh 45/20 [58] Field of Search 270/79,61, 67, 69, 80,

[56] References Cited UNITED STATES PATENTS 2,374,779 5/1945 Preston3,154,726 10/1964 McClain 270/81 X 3,322,961 5/1967 Harrison et a1.270/83 UX 3,467,370 9/1969 Grantham 270/85 3,485,492 12/1969 lltis270/84 3,589,709 6/1971 Hey et a1. 270/83 FOREIGN PATENTS ORAPPLICATIONS 1,276,660 9/1968 Germany shecf Leng h 1,436,588 3/1969Germany Primary Examiner-Wm H. Grieb Attorney, Agent, or Firm-Albert 'C.Johnston 7] ABSTRACT Large sheets such as drawings having any of variouslengths are folded into packets of standard length in the directiontransverse to the folds by feeding the sheets individually past lengthmeasuring points spaced apart along a pathway to a zigzag folder whichis actuated at intervals determined by a computing control system inresponse to signals received from sheet detectors located at themeasuring points. The detectors sense simultaneously a certain locationof the leading edge of each sheet and the presence or absense of thesheet at other points in the pathway, thus determining the foldingpattern to be applied to the sheet; and as the sheet is advanced thecontrol system measures the residual length, if any exists, by which thesheet trails a point where its presence was sensed and determinescorrespondingly the locations of certain folds. When a sheet is longerthan the length ranges defined between the detectors, its leading partis folded into panels having the desired packet length until thetrailing edge has been brought into a range between two detectors,whereupon the residual length and corresponding fold location(s) aredetermined.

20 Claims, 7 Drawing Figures FOLDING PLAN I1: L ngth PAIENTED M182 7 0143,831 .827 sum 3 or 5 Fig.2

FOLDING -A I Fowme PLAN E 50 100 150 200210 unfit 0 20 50 100 1 200 210PAIENEmuczmu sumsurs van mom Nam Eu can on. U|

METHOD AND APPARATUS FOR FOLDING SHEETS SUCH AS DRAWINGS Thisapplication is a continuation-in-part of copending US Pat. applicationSer. No. 137,549 filed Apr. 26, 1971, now abandoned the disclosure ofwhich is hereby incorporated hereinto by reference.

This invention relates to a method and apparatus for folding largesheets such as engineering drawings, photoprints thereof and othersheets commonly referred to as drawings.

In many countries the manner of folding standard sheet sizes has beenstandardized in respect of the folding program, i.e., the pattern andthe location of folds, so that a larger standard size is reduced byfolding to a small standard size, e.g. A4.

The folding of sheets is usually time consuming. For example, in thephotographic printing of large drawings, the time needed for folding maybe a multiple of the time required for printing. Automatic foldingdevices are known, but they are expensive and do not always functionsatisfactorily, particularly when nonstandard sizes are to be folded.Sometimes the apparatus can be adjusted for obtaining any desireddivision of the folds, but this is a difficult and time-consumingpractice. Non-standard sizes are usually folded like a standard size,after which the upper or lower flap is refolded, for example by hand, toprevent it from protruding too far. Alternatively, this upper or lowerflap remains shorter than with a standard size.

An object of the present invention is to improve this situation, and toprovide a way of quickly and inexpensively folding sheets, includingnon-standard size sheets, according to a logical folding program and sothat each folded sheet will have a nice appearance and be free from toolong or too short flaps.

According to the invention, as each sheet is being fed to a foldingdevice suitable for folding it at intervals in zig-zig manner, thelength of the sheet in the direction perpendicular to the folds to bemade in it is sensed so as to classify the sheet into the appropriateone of a plurality of successive length ranges, each of whichcorresponds to a preset folding pattern, and thus the folding pattern tobe used for the sheet is determined; then the amount if any by which thelength of the sheet exceeds a length reaching to the lower limit of oneof the length ranges is determined, which excess is referred to hereinas the residual length"; and the sheet then is folded according to thefolding pattern and at locations derived from the determinations of itslength range and its residual length.

The folding pattern to be used can be derived immediately andunmistakably from that one of the predetermined length ranges into whichthe length of the sheet to be folded falls, and the exact location(s)required for one or more of the folds is determined by the measurementof the residual length. This is much simpler than determining the totallength and then considering all possibilities of folding patterns andfold locations until the desired folding program has been found.Moreover, for larger sizes it is possible in this way to predeterminethe location of a first fold, for example, that of the fold nextadjacent to an edge of the folded sheet having a protruding attachmentportion, and even to start the folding operation, prior to deriving thelocations of further folds from the residual length measurement. Thus,according to the invention, the classification of the sheet length canbe performed when the leading edge of the sheet is in close proximity tothe entrance of a folding device, whereas the residual length can bemeasured after the first folding operation has already been started,e.g., by moving the sheet further into and through the folding device.

In an advantageous practice of the invention for folding sheets in whichmore than two folds are to be provided and the residual length varies,the lengths of the respective portions (flaps or panels) of the sheetsbetween their trailing edges and the fold next adjacent thereto are keptconstant. Similarly, for sheets of varying residual length and in whichmore than four folds are to be provided, the lengths of the respectiveportions (panels) between both the leading and the trailing edges of thesheet and the respective folds next adjacent (opposite) to those edgesare advantageously kept constant.

Furthermore, for sheets in at least some of the length ranges, whentheir respective residual lengths vary, the locations of twosuperimposed folds in the respective folded sheets may be variedtogether to the same extent.

The method is preferably carried out in such a way that the foldingpatterns used for sheets in the dimensional ranges which encompassstandard sheet sizes correspond with the folding patterns standardizedfor those sizes.

Further according to the invention, an apparatus is provided foreffectively carrying out the described method. This apparatus comprisesin association with a pathway, or track, along which the sheets to befolded are transported to a folding device; means for detecting thepresence of the leading edge of a sheet approaching the folding device;means for then determining the length range into which the sheet fallsby sensing the presence or absence of the sheet at detecting elementsspaced apart at locations in the pathway behind the location of thedetector of the leading edge of the sheet; means for determining theresidual length of the sheet by measuring the portion of it trailingfrom a backward point at which its presence is detected to the trailingedge of the sheet; and means for operating the folding device accordingto a folding program corresponding to the sensed length range and thedetermined residual length of each sheet to be folded.

The invention may be carried out effectively according to the embodimentdisclosed in the aforesaid copending US. Pat. application, Ser. No.137,549, for the folding of sheets having lengths not greater than thelength of a table that constitutes the pathway, or track, along whichthe sheets are fed to the folder. On the other hand, when some of thesheets tobe folded will have lengths greater than the length of such atable, such for example as lengths exceeding cm., it is advantageous tocarry out the invention according to a further development of it, suchas by the embodiment described more particularly hereinbelow.

A principal feature of this further development is that when a sheet hasreached the location adjacent to the folder where its leading edge issensed, it is determined from the action of the sheet detector at thehindmost detection point of the pathway, or table, whether the sheet islonger or shorter than the length ranges defined by the several sheetdetectors; and if it is longer, thus falling into an extra-long lengthrange, folds are made at predetermined spacing in the leading part ofthe sheet until the hindmost detector no longer senses the presence ofthe sheet, i.e., until it detects that the trail ing edge of the part ofthe sheet remaining to be folded has been brought within a length rangeboth limits of which are at determined distances from the folder. Thenthe remaining residual length of the sheet from its trailing edge up tothe lower limit of that range is measured; and from this measurement isderived the location of at least one of the folds to be made in the partof the sheet then remaining unfolded, within the folding patternemployed for sheets of its determined length range.

Thus, when a sheet is longer than the greatest length that can liebetween the measuring points provided along the pathway to the folder,the sheet is shortened by making folds in it at the desired intervalsuntil the part of it remaining to be folded lies in a measured rangebetween two of such points, whereupon the remaining residual length ofthat part and thus the location of a fold or folds to be made in it aredetermined, and it is folded, as if it were a sheet originally havingits length.

Sheets of unlimited length can be folded into packets of desiredstandard size in this way. Moreover, the maximal length betweenmeasuring points, or feed table length, can be shorter than in the caseof the first mentioned embodiment, and fewer measuring points, or sheetdetectors, can be employed; so the apparatus for carrying out theinvention can be of simpler design.

The objects, features and advantages of the invention will be furtherevident from the following description of a perferred embodiment ofapparatus and practices for carrying out the invention. This descriptionrefers to the accompanying drawings, in which FIGS. la, 1b, 1c and 1dschematically represent four sets of folding patterns suitable forcross-folding sheets having different lengths;

FIG. 2 is a schematic representation of two sets of folding plans, orpacket forms, for sheets having different lengths;

FIG. 3 is a schematic view of the sheet sensing and folding elements ofan apparatus according to the invention, in which the sheet detectingelements along the pathway to the folding device are located suitablyfor folding sheets according to plan I of FIG. 2; and

FIG. 4 is a block diagram of an electronic computer circuit forcontrolling the operations of the apparatus.

As the invention relates mainly to the folding of a sheet in a directionparallel to one edge of the sheet, the following description will relateto such folding in one direction. It is to be understood, however, thatthe invention can be used also for folding in the directionperpendicular to the direction of the first folding. When reference ismade herein to the length of the sheet, of a part of the sheet, or of afolded sheet, or packet, this refers to the dimension in the directionperpendicular to the folds which are made or to be made in the sheet.

The purpose of a folding apparatus of the kind here concerned is toreduce the dimensions of a large sheet of paper or similar material, forinstance a drawing, to smaller dimensions which preferably arestandardized, for instance to DIN A4 (210 mm.), so that it is easier tostore away the sheets. Commonly the dimensions of a large sheet are notan exact multiple of the dimensions of the desired folded packet. Forinstance, when diazotype copies are made, even from originals havingstandard dimensions, the dimensions of the copies will generally deviatefrom the standard dimensions as a result of shrinkage due to moistureand temperature differences, cutting tolerances, etc., and will thus notbe an exact multiple of the packet size wanted.

Accordingly, when a large sheet has been folded into a packet having thelength desired, one or more layers or panels will be present, so-calledintermediate folds, which are smaller than the desired length of thepacket. By an intermediate fold or panel is meant such a shorter panelor layer of the packet. Preferably not more than two intermediate foldswill be provided, as in this way the packet contains a minimal number oflayers having less than the desired length. This, how ever, involves thefollowing difficulty.

In the case of only two intermediate panels, the length of each of themis equal to half the difference between the length of the non-foldedsheet and the greatest multiple, smaller than that length, of thedesired length of the packet. This means that in practice smallintermediate panels will occur, especially when the length of the sheetis only slightly greater than a multiple of the desired packet length,as often is the case. Aside from the fact that it is hardly practicableto fold them, such short intermediate panels are not aesthetic, and theytend to make the packet considerably thicker at one side than at theother, so that difficulties may result when storing the packets.

For this reason, a minimal length for the intermediate panels ispreferably maintained. Since the intermediate panels must contain thedifference between the length of the sheet and the amount of its lengthfolded into panels having the desired packet length, when the maximalnumber of the latter is provided the intermediate panels will each haveat most a length equal to half the desired packet length. Practically,this means that when folding a sheet into, for example, size DIN A4having a length of 210mm, the intermediate panels would each have alength of at most mm if the packet contained the greatest practicablenumber of panels having the desired packet length. Accordingly, if aminimal panel length of more than 105 mm is to be assured, this requiresin certain cases that more than two panels of the packet must be madeshorter than the length of the packet.

FIG. 1a shows schematically variations of the folding pattern suitablefor various lengths of the sheets, for a practice in which each sheet isfolded into a packet having a length of 210 mm and an intermediate panellength of at least 105 mm. In FIG. lathe abscissa represent the originallengths of the sheets, while the ordinates represent the lengths of thepacket panels, or layers. The number of layers necessary in order toreduce a certain sheet to the length of the packet is represented by thenumber of ordinate lines shown at the abscissa point corresponding tothe length of the sheet. For sheet lengths up to 210 mm no fold isnecessary. When the sheet is longer than 210 mm but shorter than 420 mm,the sheet is folded once, so that each panel is slightly longer than 105mm if the sheet is but slightly longer than 210 mm and the panel lengthgradually increases to 210 mm as the length of the sheet increases to410 mm. The sloped parallel lines extending between point 105, 210 andpoint 210, 420 represent the progression.

At sheet lengths between 420 and 630 mm the packet consists of threelayers, including a first layer constantly of 210 mm length, asrepresented by the horizontal line at ordinate 210, and two intermediatepanels the length of which gradually increases from 105 to 210 mm as thelength of the sheet increases from 420 to 630 mm. The same pattern isrepeated for sheet lengths between 630 and 840 mm, between 840 and 1,050mm, etc., excepting that two, three, or a larger number of layers areformed with the constant packet length of 210 mm. For the sheets in eachrange two intermediate panels are formed with lengths which vary between105 and 210 mm. The use of a smaller length for the minimal intermediatepanel gives no extra advantage. At certain sheet lengths a choice can bemade between folding patterns.

In practice it is often desirable that the free edge of the bottom layerof the folded packet be situated at the left-hand side, so as to be seenwith the sheet, such as a drawing, in the normal posture for reading it.On the other hand, it is also desirable that the free edge of the toppanel be situated at the right-hand side, so that the legend on thedrawing, if any, can easily be identified. In order to fulfill theserequirements, it is necessary that the packet be composed of an oddnumber of layers, or, which means the same thing, that the sheet befolded with an even number of fold lines.

If then a minimal intermediate panel length is to be assured, it isnecessary in the case of sheets having a length greater than aneven-number multiple of the de sired packet length but smaller than thenext higher odd-number multiple thereof, to provide two intermediatepanels in the packet; while in the case of sheets having a lengthgreater than an odd-number multiple of the desired packet length butsmaller than the next higher even-number multiple thereof, at least fourintermediate panels must .be provided. I-Iere also there is a maximallength for the intermediate panels.

In the former case, of the sheet length being greater than an evennumber of packet lengths such that two intermediate panels must beprovided, the same condition as mentioned above applies, namely, thatthe length of each intermediate panel is at least half of and at mostequal to the desired packet length. In the second case, the sum of theminimal intermediate panel lengths must be between two and three timesthe desired packet length; so in the second case the lengths of theminimal intermediate panels can be chosen differently for differentpairs of them. If their lengths are chosen to be at least half of thepacket length, a folding pattern as represented schematically in FIG. lbis obtained.

FIG. 1b too is based, for example, on folding the sheets into a DIN A4length of 210 mm. For a given point (sheet length) selected along theabscissa, the full lines on the ordinate from that point represent thenumber and the respective lengths of the panels (lay-' ers) of thepacket formed by folding the sheet. The lengths of the intermediatepanels are in this case at least I05 mm.

Another possible pattern for forming the desired packets is representedin FIG. 10, where in the cases of sheet lengths requiring at least fourintermediate panels the lengths of these panels are chosen differentlyfor different pairs of them. In this example there are two intermediatepanels of minimally 120 mm and two intermediate panels of minimally 90mm. In practice according to this example, as the sheet lengths increasewithin a certain range the lengths of the intermediate panels ofminimally 120 mm can be increased first, until these have reached theirmaximum, after which the lengths of the intermediate panels of minimallymm increase until these have reached their maximum. Conversely, it isalso practicable to keep the intermediate panels of minimally mmconstant while first allowing the intermediate panels of minimally 90 mmto increase gradually, as represented by the broken lines in FIG. 1c.

Further in the case of FIG. 1c, for instance at sheet lengths increasingin the range between 630 and 1,050 mm, i.e., from 3 to 5 times thepacket length, the four intermediate panels can be gradually increasedsimultaneously.

Finally, FIG. id represents a third variant whereby intermediate panelsof minimally 60 mm and mm, respectively, are provided in the packets.

In principle, it is of course also practicable when working with lengthswhich require at least four inter mediate panels to make these panels soshort that the sum of their lengths is smaller than the packet length.Also, more than four intermediate panels can be formed.

The invention preferably is carried out by the use of folding patternsaccording to FIG. 1c, for the following reasons.

In the folding of sheets according to FIG. la and lb, the foldingpattern of a sheet slightly longer than a multiple of the desired packetlength is different from that of a sheet slightly shorter than the samemultiple. The desired packet length is commonly standardized. If some ofthe sheets to be folded have lengths nominally equal to a multiple ofthe desired packet length, but which in fact vary within certaintolerances, then various of these sheets will be folded in two differentways.

This disadvantage can be avoided to a great extent, upon taking intoconsideration the fact that the nominal sheet lengths normally are aneven-number multiple of the standardized packet length, by using thefolding patterns according to FIG. 10 or FIG. 1d. Among these thefolding patterns according to FIG. 10 are preferred. Therefore, thefollowing description will only deal with this manner of folding.

FIG. 2 schematically represents. two folding plans for cross-foldingsheets of the standard sizes A3, A2, A1 and A0 into packets of A4 size,so as to produce either packets of 210 mm in length without a marginalfastening strip or packets of mm in. length having a marginal fasteningstrip of 20 mm in length (distance of protrusion from an edge of thepacket). This figure also illustrates folding patterns suitable forvarious sheet lengths intermediate those of the standard sizes. Foldingplan I of FIG. 2 corresponds with the folding patterns represented bythe schematic showings in full lines on FIG. 1c.

FIG. 3 shows schematically at the left-hand side thereof a device ofknown type for folding sheets in zigzag manner. This device includes twopairs 1 and 2 of folding rollers which are reversible in theirrespective directions of rotation and a guide element 4 which can bemoved back and forth between a position indicated at 3, in which itdirects a sheet, or part of a sheet, into the bite of rollers 2, and aposition indicated at 3 in which it directs the sheet or a part of itinto the bite of rollers l. Rollers feed into the guide 4 a sheet guidedto them by a channel 6 into which the sheet is fed by rollers 7 from atable 8. When a sheet is introduced into the folder by the rollers 7, ifthe guide element 4 is in position 3 the sheet is picked up by therollers 1, and when a folding signal is given the direction of rotationof the roller pairs 1 and 2 is reversed and the guide element 4 is movedto position 3. Thus an undulation is formed in the sheet below the guideelement 4, and this undulation is picked up by the rollers 2 so as tomake a fold in the sheet at its location. By returning the guide elementto position 3' and reversing the direction of rotation of the rollers 1and 2, a second fold in the direction opposite to that of the first foldis made in the sheet. By continuing the operations in the way describedthe sheet can be folded zig-zig as many times as required, until it iscompletely folded in the desired packet and delivered through thefolding rollers of pair 1 or pair 2.

Of course, other known types of zig-zag sheet folders can be usedinstead of the type illustrated in the drawmg.

The signals for moving the guide element back and forth and reversingthe direction of rotation of the rollers 1 and 2 are produced by theaction of sheet detectors spaced apart along the pathway of the sheetsfed over the table 8 into the folding device and the action of thecomputing control system shown diagrammat ically in FIG. 4.

A first sheet sensing element or detector FDO is located in the channel6 in a position to sense the presence of the leading edge of a sheetentering the folder. Sheet detectors FD], FD2, FD3 and FD4 are locatedin the sheet feed table 8 at distances from detector FDO correspondingto the limits of the sheet length ranges for which the various foldingpatterns are suited. The locations of these elements as represented inFIG. 3 are adapted to folding plan I of FIG. 2 and the correspondingshowings of FIG. 10; so the operations of the folder as described ingreater detail below relate in each instance to the folding of a sheetaccording to a pattern as represented in FIG. 1c and in the left-handcolumn of FIG. 2.

As explained in detail below, all the detectors, or sheet sensingelements, are activated by a signal from element FDO which is emitted assoon as the leading edge of a sheet arrives at FDO. Each detector thensenses whether or not a part of the sheet is present at its location,and the hindmost of those of the detectors which sense the presence of apart of the sheet determines the first two folds which are then made.

If none of the detectors FDl through FD4 senses the presence of a sheetthat has reached the location of FDO, the sheet ordinarily is notfolded. However, such a short sheet can, of course, be folded in themanner described in the aforesaid copending application.

If detector FD4 senses the presence of the sheet, then two folds aremade in the forward part of the sheet so that the distance between theleading edge and the first fold is equal to the desired packet length(e.g., 210 mm) or to that length plus the length of a fastening strip(e.g., 190 mm), and the distance between the first and second folds isequal to the desired packet length. Then, while the sheet keepsadvancing over the table into the folder, detector FD4 senses whetherthe distance between the second fold and the trailing edge of the sheetcontinues to be greater or has become smaller than the distance betweenFDO and FD4. If element FD4 still senses the presence of a part of thesheet, then two additional folds are made in the advance part of thesheet so that the distance between the successive folds 5 is each timeequal to the desired packet length. This manner of folding panels two bytwo is repeated until the detector FD4 no longer senses the presence ofthe sheet, i.e., until the distance between the fold last made and thetrailing edge is smaller than the distance between FDI) and FD4.

If the detector FD4 does not sense, or when it no longer senses, a partof the sheet, the other detectors along the feed table determine betweenwhich two of the detectors the trailing edge of the sheet lies at themoment when the leading edge of the sheet, or the lo cation of the lastprevious fold to be made in the sheet, lies opposite to detector FDO.

If the trailing edge is then determined to lie between FD3 and FD4, twofolds are made at intervals of 90 mm, the first of those being at adistance of 90 mm from the leading edge or the next preceding fold. Asthese two folds are being made the trailing edge moves past detectorFD3. Since the sheet is advanced at a constant speed, the exact amountby which the length of the sheet, or of the part of it remaining to befolded, exceeds the distance between detectors FDO and FD3 can bedetermined by determining the time of the travel of its trailing edgefrom the location it occupied when determined to be lying between FD3and FD4, to the location of detector FD3. The length of this trailingpart of the sheet as so determined represents the residual length of thesheet and determines the locations where the folds of the next pair areto be made in the sheet.

Thus, after the two folds at intervals of 90 mm are made in the sheet,the two following folds are each made at a distance of 120 mm plus halfthe residual length, measured from the next preceding fold. Then a finalpanel of 210 mm in length remains, corresponding to the desired lengthof the packet.

If the length of the sheet to be folded is such that the trailing edgelies between FD2 and FD3 when the leading edge or the location of thelast previous fold to be made is at FDO, the residual length is measuredin relation to FD2, and two folds are made each at a distance of 120 mmplus half the residual length from the leading edge or the last previousfold. Again, a panel of 210 mm in length remains, corresponding to thedesired packet length.

If, instead, the trailing edge then lies between FDI and FD2, theresidual length is measured in relation to FDI, and intermediate foldsare made at a distance of 90 mm plus half the residual length from theleading edge or the last previous fold.

As appears from FIG. 1c, the same folding pattern is used whether thetrailing edge lies between FDI and FD2 or between FD2 and FD3; so,theoretcially, it would be possible to omit detector FD2. Practicallythis is not feasible without unduly complicating the control system,because the residual length could not then be determined due to thepre-requisite of the system as illustrated in FIG. 3 that when thetrailing edge lies between FD2 and FD3, the next fold to be made will beat least 120 mm distant from the leading edge or the last precedingfold. The sheet can be advanced further through this distance withoutrisk of losing control of the fold location, for the trailing edge willpass detector FD2 during this movement, whereupon the residual lengthand thus the location of the next fold can be determined. When thetrailing edge has not yet passed detector FD2, the remaining length ofthe sheet portion from the location of the first fold to the trailingedge must also be at least 120 mm, and since half of this length is atleast 60 mm, the location of the second next fold certainly lies atleast 60 mm further. While the sheet is being advanced through adistance of at least 180 mm, its trailing edge certainly passes detectorFD2 to enable determination of the exact value of the residual lengthand the exact location of the fold. If, however, detector FD2 were notpresent, the sheet could have been advanced by more than 180 mm whileits trailing edge continued to lie between FDI and FD3; and if itstrailing edge thus had not yet passed detector FDl, then the residuallength could not be determined unless the control system were far morecomplicated.

Summarizing, folds are made in each sheet at locations as indicated inthe following table, which relates to a packet length of either 210 mmor 190 mm and indicates fold locations as distances (lengths) in mmpreceding the respective folds. The folding pattern for a packet lengthof 190 mm having a fastening strip of 20 mm (folding plan II in FIG. 2)can be derived from the folding pattern for a packet length of 190 mm byincreasing the length of the first fold panel of the sheet by 20 mm. Howthis is effected will be explained below.

The operation of the control system of the folding apparatus will beexplained below by reference to the block diagram of FIG. 4.

The detectors FDO up to and including FD4 produce signals whichrepresent the presence or the absence of the paper or other sheet beingtransported along the table 8 or other pathway so as to be sensed bythese elements. These signals are converted by a converter 10 intological command signals (I state or state). The system includes pulsediscs FCv and FCm which are coupled to the sheet transporting movementof the folding rollers or the feed rollers and 7, and which transmitcounting pulses to the converter 10.

A logical command signal Cm is thus generated for use to measure theresidual length. Also, a signal Cv is generated for counting off theprogrammed and calculated folding length.

The control system remains in an inactive or rest condition as long asdetector FDO is not activated. However, as soon as the leading edge of asheet arrives at the location of detector FDO, a starting generator 11is actuated by a signal FDO issued by the convertor 10. The startinggenerator 11 now generates a signal Do. This signal can have a delay orretardation time, so that the sheet will advance a distance equal to thelength of the side fastening strip during the delay time. Upon thecommand of signal Do the conditions of the signals D1 up to andincluding D4 are recorded in a buffermemory unit 12. Depending uponthese conditions recorded in the buffer-memory unit 12, the programregister 13 determines which one of the folding programs G1, G2 G5 (seeTable A), is to be executed. If program G2 or G3 is indicated, so aprogram with a variable folding length, the program register 13 byemission Gi simultaneously actuates a selection circuit 14 and opens agate 15 to let the residual length counting pulses Cm pass through thisgate. The third input of gate 15 is the sheet direction signal Di. Theresidual length counting pulses Cm are then transmitted via gate 15 to atwo-divider 16 which halves the frequency of the pulse signal Cm, sothat half of the residual length /2A) is measured in a residual lengthcounter 17. When the sheet of paper again uncovers the detector FD2 orFD3, the gate 15 closes so that the counting pulses Cm are no longerpermitted to pass. The residual length determination has then beenfinished.

A gate 18 in the circuit has three entries, into which the signals FDO,Cv and Q0 are transmitted. The signal Q0 is an inversion of the 00signal which originates from the selection circuit 14. The signal Q0initially has the 1 state.

Gate 18 is opened by signal FDO, so that the counting pulses Cv will betransmitted to a counter 19. A decoding unit 20, in which the fixedvalues of Table A are recorded, determines when the fixed number ofpulses of the program G2 or G3 (e.g., pulses equivalent to a distance ofor mm) has been counted. The output signal Ni of the decoding unit 20then actuates the selection circuit 14, so that the condition of the Q0signal modifies. Thus the gate 18 is blocked, so that the countingpulses Cv are no longer conducted to the counter 19. The pulses Cv stillto follow are now transmitted to a counter 22 via a gate 21, which isopened by the signal Q0.

During the counting the content of the counter 22 is continuallycompared by a comparing unit 23 with the content of the residual lengthcounter 17. When the contents of the counters l7 and 22 are equal, asignal S is generated, which in cooperation with the 00 signal opens agate 24, so that a folding pulse T is generated.

When the program register 13 establishes that the folding program to beexecuted is one having no variable factor, a selection circuit 25 isactuated by the Gi signal of the program register 13 and by the Nisignal of the decoding unit 20. The Ni signal is generated after thefixed folding length recorded in decoding unit 20 has been counted. Thusa pulse R is generated, which in turn generates a folding pulse T viagate 24.

At the start of the feeding of the sheet, the sheet moves through guide4 to the left and between the folding rollers l. The folding pulsegenerated as described above actuates a two-divider 26, so that one ofthe two outputs of this two-divider, in this case the signal VR,receives the 1 state. Upon this signal the direction of rotation of thefolding rollers l and 2 is reversed, and a fold is formed. The sheet nowis guided by element 4 in the direction to pass to the right between thefolding rollers 2. The folding pulse T serves also as a reset signal bywhich the counters l9 and 22 are brought back into their zero position,while the buffer memory 12, the program register 13 and the residuallength counter 17 keep in the same condition. Now the same foldinglength as that for the first fold is measured off, after which a secondfolding pulse T is generated and the VL signal from divider 26 receivesthe 1 state.

By this second folding pulse the direction of rotation of the foldingrollers 1 and 2 is again reversed, and the counters 19 and 22 arebrought back into their zero position. Because the VL signal hasreceived the 1 state, the residual length counter is now set back to thezero position, and the signals of the detection elements at that momentare again recorded in the memory unit; so a new folding program can nowbe selected by the control system.

Thus, after each two folds the whole circuit is restored to its originalcondition, and it immediately makes a new observation of the position ofthe sheet relative to the detectors FDl FD4, for the following two foldsif the remaining length of the sheet not yet folded is such that morefolds are required. This cycle is repeated until the entire sheet hasbeen folded into the selected packet length. For instance, two foldsmade according to program G may be followed by two folds made accordingto program G2, if the sheet is of A1 length (841 mm); or may be followedby two folds made at 90 mm intervals according to program G4, and thenby two more folds made at 189.5 mm intervals according to program G3, ifthe sheet is of A0 length 1,189 mm). The corresponding packet forms areillustrated in FIG. 2, Plan I.

It will be evident to those skilled in the art that the invention is notlimited to the example described above and that numerous modificationscan be employed without departing from the substance of the invention,which is intended to be defined by the appended claims.

What is claimed is:

1. A method of folding large sheets having any of various lengthsindividually into respective packets having a desired standard length inthe direction transverse to the folds, which comprises: feeding thesheets individually along a measuring pathway to and then through afolding means operable to form in a sheet moving therethrough successivefolds in zigzag disposition at locations spaced apart along the sheet;as each sheet moves to said folding means determining in which one of aplurality of successive predetermined sheet length ranges the length ofthe sheet lies by sensing simultaneously a certain location of theleading edge of the sheet and the presence or absence of the sheet atrespective points spaced apart along said pathway at the limits of saidlength ranges, and measuring the residual length if any exists by whichthe sheet then trails behind the lower limit of one of said lengthranges; and as the sheet moves through said folding means operating thelatter at successive intervals the number and the respective distancesof which, so the number and spacings of said folds formed in the sheet,are determined according to the magnitudes of said determined lengthrange and said residual length.

2. A method according to claim 1, said feeding of the sheets beingeffected at a determined speed and said measuring of the residual lengthof each sheet being effected by measuring the time of the travel of thetrailing edge of the sheet from a sensed location thereof between two ofsaid points to the location of the one of said two points nearer to saidfolding means.

3. A method according to claim 1, as applied to sheets having lengths ofabout two to between three and four times said desired packet length,which comprises forming in each sheet an even number of said folds, withthe last of said folds at a distance from said trailing edge equal tosaid desired packet length and with the first of said folds at alocation such that said leading edge lies in the formed packet at adistance from said trailing edge equal to said packet length or to thesame plus the width of an end strip of the sheet provided for attachmentof the formed packet, and forming said first and last folds and anyintermediate folds at respective distances from the respective nextpreceding folds and said leading edge which do not exceed said packetlength and the sum of which is equal to the length of the sheet lesssaid packet length.

4. A method according to claim 1, as applied to sheets having lengths ofthree to four or more times said desired packet length, which comprisesforming in each sheet an even number of said folds, with the first ofsaid folds at a distance from said leading edge approximately equal tosaid desired packet length or to the same plus the width of an end stripof the sheet provided for attachment of the formed packet, and with thelast of said folds at a distance from said trailing edge equal to saidpacket length, and forming in the sheet between the first and last foldsat least two intermediate folds at respective distances from therespective next preceding folds which correspond to a fraction of saidpacket length plus an even-number fraction of said residual length butdo not exceed said packet length.

5. A method according to claim 4, wherein, when the sheet length liesbetween an even-number multiple and the next higher odd-number multipleof said packet length, two of such intermediate folds at such respectivedistances are formed in the sheet and any other intermediate foldtherein is formed at a distance approximately equal to said packetlength from the fold next preceding it.

6. A method according to claim 4, wherein, when the sheet length liesbetween an odd-number multiple and the next higher even-number multipleof said packet length, four of such intermediate folds at suchrespective distances are formed in the sheet and any other intermediatefold therein is formed at a distance approximately equal to said packetlength from the fold next preceding it.

7. Apparatus for folding large sheets having any of various lengthsindividually into respective packets having a desired standard length inthe direction transverse to the folds, including folding means operableby successive impulses to form in a sheet moving therethrough successivefolds in zig-zag disposition at locations spaced apart along the sheet,a table defining a sheet measuring pathway, and means for feeding thesheets individually along and from said table to and then through saidfolding means, sheet detection means including an element for sensing ata certain location the leading edge of a sheet moving to said foldingmeans and a plurality of elements associated with said table forsimultaneously sensing the presence or absence of said sheet atrespective points spaced apart along said pathway, said points beinglocated at the lower limits of a plurality of successive sheet lengthranges so that a particular one of said ranges in which said sheet liesis determined by the operation of said sensing elements, means operativewhen said particular length range is determined for measuring theresidual length if any exists by which the sheet then trails the lowerlimit of one of said length ranges, and control means responsive to saiddetection means and to said measuring means for operating said foldingmeans at successive intervals the number and the distances of which, sothe number and spacings of said folds formed in the sheet, aredetermined according to the magnitudes of said determined length rangeand said residual length.

8. Apparatus according to claim 7, said sheet feeding means beingoperative to feed each sheet at a determined speed and said means formeasuring said residual length including means for measuring the time ofthe travel of the trailing edge of the sheet from a sensed locationthereof between two of said points to the location of the one of saidtwo points nearer to said folding means.

9. Apparatus according to claim 7, said means for measuring saidresidual length comprising a pulse sender emitting pulses having afrequency proportional to the speed at which the sheet is fed to saidfolding means and means for counting said pulses during the time periodof movement of the trailing edge of the sheet from a location thereofsensed to be between two of said points to the one of said two pointsnearer to said folding means.

10. Apparatus according to claim 7, said control means including memorymeans for recording signals corresponding to the conditions sensed bysaid sensing elements, register means for progressively sensing arepetitive clock signal, and means for comparing the state of signalssensed by said register means with that of the signals recorded by saidmemory means and fixing a signal output of said register meanscorresponding to a condition thereof in which the signal input theretocorresponds in extent to the signals recorded by said memory means whena sheet is sensed at the lower limit of said determined length range.

11. Apparatus according to claim 7, said means for measuring saidresidual length comprising a pulse sender emitting pulses having afrequency proportional to the speed at which the sheet is fed to saidfolding means and means for counting said pulses during the time periodof movement of the trailing edge of the sheet from a location thereofsensed to be between two of said points to the one of said two pointsnearer to said folding means, said control means including memory meansfor recording signals corresponding to the conditions sensed by saidsensing elements, register means for progressively sensing a repetitiveclock signal, and means for comparing the state of signals sensed bysaid register means with that of the signals recorded by said memorymeans and fixing a signal output of said register means corresponding toa condition thereof in which the signal input thereto corresponds inextent to the signals recorded by said memory means when a sheet issensed at the lower limit of said determined length range.

12. Apparatus according to claim 11, and means for blocking access ofsaid pulses to said counting means when the condition sensed by thesensing element at said lower limit changes from the presence to theabsence of the sheet.

l3. Apparatus according to claim 12, said blocking means including apulse generator for comparing said signal output of said register meanswith signals corresponding to the conditions sensed by said sensingelements and gate means responsive to a signal from said generator tostop passage of said pulses to said counting means.

14. Apparatus according to claim 11, further comprising means forconverting said pulses into signals having either of two reducedfrequencies and means controlled by said signal output of said registermeans for selecting and transmitting to said counting means the signalshaving one of said redluced frequencies.

15. Apparatus according to claim 12, further com prising means foremitting a pulse to complete the operating of said folding means afterthe occurrence of a number of said pulses corresponding to saidcondition of said register means and the input of said counting means.

16. Apparatus for folding large sheets having any of various lengthsindividually into respective packets having a desired standard length inthe direction transverse to the folds, including folding means operableby successive impulses to forms in a sheet moving there throughsuccessive folds in zig-zag disposition at locations spaced apart alongthe sheet and means for feeding the sheets individually along and from afixed pathway to and then through said folding means, sheet detectionmeans including a first element for sensing at a certain location theleading edge of a sheet moving to said folding means and a plurality ofelements at points spaced apart along said pathway for simultaneouslysensing the presence or absence of said sheet at respective ones of saidpoints, means operative to actuate said folding means so as to make apredetermined number of initial folds at predetermined spacings in thesheet if when the leading edge of the sheet reaches said first elementthe presence of the sheet is sensed at the hindmost of said points, andto repeat such actuation of said folding means if after said number offolds the presence of the sheet is still sensed at said hindmost point,until the trailing edge of the sheet lies in a length range between twoof said points, and means operative when the trailing edge of the sheetis sensed to lie between two of said points, either at the time of theleading edge reaching said first element or upon such initial foldshaving been made in the sheet, to select a folding pattern suited forthe length range defined between said two points, then to measure thedistance if any by which the trailing edge of the sheet lies behind theone of said two points nearer to said folding means, and to actuate saidfolding means so as to make final folds in the sheet in a number and atlocations derived from said pattern and from said measured distance.

17. Apparatus according to claim 16, said predetermined spacings beingequal to the desired length of the packets being formed by the foldingof the sheets.

18. Apparatus according to claim 16, said predetermined number ofinitial folds being two.

19. Apparatus according to claim 16, the number of said final foldsbeing two.

20. Apparatus according to claim 16, said last recited means beingoperative to make two such final folds in the sheet when the said lengthrange is greater than an even-number multiple but less than the nexthigher odd-number multiple of the desired length of the packet intowhich the sheet is being folded, and to make four such final foldstherein when said length range is greater than an odd'number multiplebut less than the next higher even-number multiple of said desiredpacket length.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. ,9 1Dated August 2'7, 197

Inventor(s) Josef Marie Jan Verten It is certified that error appears inthe above-identified patent and that said Letters Patent are herebycorrected as shown below:

Column line 65, chair-gs "to to read to 120 mm.

Signed and Sealed this nineteenth D f August 1975 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Altesling ()ffieer (mnmissimu'r 0fParents and Trademarks FORM P0-1050 (10459) uscoMM-oc wan-p09 u.s.covzmmern nuu'rmc ornc: B69. 930

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 5, 51,97 Dated August 197Lt Inventor(s) Josef Marie van Herten Q It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

In the heading, beneath Foreign Application Priority Data" should read:Apr. 2h, l970 Netherlands 7006050 Column 10, line 27, "00" should read00 Column 10, line 28, the first "00" should read 0o Column 10, line 29;"00" should-' read 0o Signed and Emalcd this twenty-third Of March 1976[SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner oj'Patenlsand Trademarks G

1. A method of folding large sheets having any of various lengthsindividually into respective packets having a desired standard length inthe direction transverse to the folds, which comprises: feeding thesheets individually along a measuring pathway to and then through afolding means operable to form in a sheet moving therethrough successivefolds in zigzag disposition at locations spaced apart along the sheet;as each sheet moves to said folding means determining in which one of aplurality of successive predetermined sheet length ranges the length ofthe sheet Lies by sensing simultaneously a certain location of theleading edge of the sheet and the presence or absence of the sheet atrespective points spaced apart along said pathway at the limits of saidlength ranges, and measuring the residual length if any exists by whichthe sheet then trails behind the lower limit of one of said lengthranges; and as the sheet moves through said folding means operating thelatter at successive intervals the number and the respective distancesof which, so the number and spacings of said folds formed in the sheet,are determined according to the magnitudes of said determined lengthrange and said residual length.
 2. A method according to claim 1, saidfeeding of the sheets being effected at a determined speed and saidmeasuring of the residual length of each sheet being effected bymeasuring the time of the travel of the trailing edge of the sheet froma sensed location thereof between two of said points to the location ofthe one of said two points nearer to said folding means.
 3. A methodaccording to claim 1, as applied to sheets having lengths of about twoto between three and four times said desired packet length, whichcomprises forming in each sheet an even number of said folds, with thelast of said folds at a distance from said trailing edge equal to saiddesired packet length and with the first of said folds at a locationsuch that said leading edge lies in the formed packet at a distance fromsaid trailing edge equal to said packet length or to the same plus thewidth of an end strip of the sheet provided for attachment of the formedpacket, and forming said first and last folds and any intermediate foldsat respective distances from the respective next preceding folds andsaid leading edge which do not exceed said packet length and the sum ofwhich is equal to the length of the sheet less said packet length.
 4. Amethod according to claim 1, as applied to sheets having lengths ofthree to four or more times said desired packet length, which comprisesforming in each sheet an even number of said folds, with the first ofsaid folds at a distance from said leading edge approximately equal tosaid desired packet length or to the same plus the width of an end stripof the sheet provided for attachment of the formed packet, and with thelast of said folds at a distance from said trailing edge equal to saidpacket length, and forming in the sheet between the first and last foldsat least two intermediate folds at respective distances from therespective next preceding folds which correspond to a fraction of saidpacket length plus an even-number fraction of said residual length butdo not exceed said packet length.
 5. A method according to claim 4,wherein, when the sheet length lies between an even-number multiple andthe next higher odd-number multiple of said packet length, two of suchintermediate folds at such respective distances are formed in the sheetand any other intermediate fold therein is formed at a distanceapproximately equal to said packet length from the fold next precedingit.
 6. A method according to claim 4, wherein, when the sheet lengthlies between an odd-number multiple and the next higher even-numbermultiple of said packet length, four of such intermediate folds at suchrespective distances are formed in the sheet and any other intermediatefold therein is formed at a distance approximately equal to said packetlength from the fold next preceding it.
 7. Apparatus for folding largesheets having any of various lengths individually into respectivepackets having a desired standard length in the direction transverse tothe folds, including folding means operable by successive impulses toform in a sheet moving therethrough successive folds in zig-zagdisposition at locations spaced apart along the sheet, a table defininga sheet measuring pathway, and means for feeding the sheets individuallyalong and from said table to and then through said folding means, sheetdetection means including an element for sensing at a certain locationthe leading edge of a sheet moving to said folding means and a pluralityof elements associated with said table for simultaneously sensing thepresence or absence of said sheet at respective points spaced apartalong said pathway, said points being located at the lower limits of aplurality of successive sheet length ranges so that a particular one ofsaid ranges in which said sheet lies is determined by the operation ofsaid sensing elements, means operative when said particular length rangeis determined for measuring the residual length if any exists by whichthe sheet then trails the lower limit of one of said length ranges, andcontrol means responsive to said detection means and to said measuringmeans for operating said folding means at successive intervals thenumber and the distances of which, so the number and spacings of saidfolds formed in the sheet, are determined according to the magnitudes ofsaid determined length range and said residual length.
 8. Apparatusaccording to claim 7, said sheet feeding means being operative to feedeach sheet at a determined speed and said means for measuring saidresidual length including means for measuring the time of the travel ofthe trailing edge of the sheet from a sensed location thereof betweentwo of said points to the location of the one of said two points nearerto said folding means.
 9. Apparatus according to claim 7, said means formeasuring said residual length comprising a pulse sender emitting pulseshaving a frequency proportional to the speed at which the sheet is fedto said folding means and means for counting said pulses during the timeperiod of movement of the trailing edge of the sheet from a locationthereof sensed to be between two of said points to the one of said twopoints nearer to said folding means.
 10. Apparatus according to claim 7,said control means including memory means for recording signalscorresponding to the conditions sensed by said sensing elements,register means for progressively sensing a repetitive clock signal, andmeans for comparing the state of signals sensed by said register meanswith that of the signals recorded by said memory means and fixing asignal output of said register means corresponding to a conditionthereof in which the signal input thereto corresponds in extent to thesignals recorded by said memory means when a sheet is sensed at thelower limit of said determined length range.
 11. Apparatus according toclaim 7, said means for measuring said residual length comprising apulse sender emitting pulses having a frequency proportional to thespeed at which the sheet is fed to said folding means and means forcounting said pulses during the time period of movement of the trailingedge of the sheet from a location thereof sensed to be between two ofsaid points to the one of said two points nearer to said folding means,said control means including memory means for recording signalscorresponding to the conditions sensed by said sensing elements,register means for progressively sensing a repetitive clock signal, andmeans for comparing the state of signals sensed by said register meanswith that of the signals recorded by said memory means and fixing asignal output of said register means corresponding to a conditionthereof in which the signal input thereto corresponds in extent to thesignals recorded by said memory means when a sheet is sensed at thelower limit of said determined length range.
 12. Apparatus according toclaim 11, and means for blocking access of said pulses to said countingmeans when the condition sensed by the sensing element at said lowerlimit changes from the presence to the absence of the sheet. 13.Apparatus according to claim 12, said blocking means including a pulsegenerator for comparing said signal output of said register means withsignals corresponding to the conditions sensed by said sensing elementsand gate means responsive to a signal from said generator to stoppassage of said pUlses to said counting means.
 14. Apparatus accordingto claim 11, further comprising means for converting said pulses intosignals having either of two reduced frequencies and means controlled bysaid signal output of said register means for selecting and transmittingto said counting means the signals having one of said reducedfrequencies.
 15. Apparatus according to claim 12, further comprisingmeans for emitting a pulse to complete the operating of said foldingmeans after the occurrence of a number of said pulses corresponding tosaid condition of said register means and the input of said countingmeans.
 16. Apparatus for folding large sheets having any of variouslengths individually into respective packets having a desired standardlength in the direction transverse to the folds, including folding meansoperable by successive impulses to forms in a sheet moving therethroughsuccessive folds in zig-zag disposition at locations spaced apart alongthe sheet and means for feeding the sheets individually along and from afixed pathway to and then through said folding means, sheet detectionmeans including a first element for sensing at a certain location theleading edge of a sheet moving to said folding means and a plurality ofelements at points spaced apart along said pathway for simultaneouslysensing the presence or absence of said sheet at respective ones of saidpoints, means operative to actuate said folding means so as to make apredetermined number of initial folds at predetermined spacings in thesheet if when the leading edge of the sheet reaches said first elementthe presence of the sheet is sensed at the hindmost of said points, andto repeat such actuation of said folding means if after said number offolds the presence of the sheet is still sensed at said hindmost point,until the trailing edge of the sheet lies in a length range between twoof said points, and means operative when the trailing edge of the sheetis sensed to lie between two of said points, either at the time of theleading edge reaching said first element or upon such initial foldshaving been made in the sheet, to select a folding pattern suited forthe length range defined between said two points, then to measure thedistance if any by which the trailing edge of the sheet lies behind theone of said two points nearer to said folding means, and to actuate saidfolding means so as to make final folds in the sheet in a number and atlocations derived from said pattern and from said measured distance. 17.Apparatus according to claim 16, said predetermined spacings being equalto the desired length of the packets being formed by the folding of thesheets.
 18. Apparatus according to claim 16, said predetermined numberof initial folds being two.
 19. Apparatus according to claim 16, thenumber of said final folds being two.
 20. Apparatus according to claim16, said last recited means being operative to make two such final foldsin the sheet when the said length range is greater than an even-numbermultiple but less than the next higher odd-number multiple of thedesired length of the packet into which the sheet is being folded, andto make four such final folds therein when said length range is greaterthan an odd-number multiple but less than the next higher even-numbermultiple of said desired packet length.